Self-consolidated concrete (SCC) is increasingly being used for both precast and ready mixed concrete applications. For ready mixed concrete, slump flow retention becomes a concern when the concrete is transported for long distance, and when delays in placing the concrete occur due to unexpected traffic problems or incomplete jobsite preparations. In this study, the performance of a special multifunctional superplasticizer is discussed that can enable SCC mixtures to have slump flow retention up to two hours without any significant extended setting properties and delay in strength gain. Furthermore, during the period of extended slump-flow, the SCC demonstrates rheological properties adequate to ensure segregation resistance once the concrete has been placed, as well as good moisture tolerance. This capability provided by the special superplasticizer formulation is expected to significantly reduce quality control operations and facilitate the successful production and placement of self-consolidating ready mixed concrete by imparting an appropriate amount of thixotropy to the SCC mixture without compromising suitable flow properties.

Ultra-high-performance concrete (UHPC) possesses a very low watercement ratio (< 0.25). Additionally, a large amount of fines, such as silica fume, are used to achieve optimum packing density. Because of its specific surface chemistry and higher surface area, silica fume is more difficult to disperse than cement. Previously, it was found that methacrylic acid-MPEG methacrylate ester type PCEs disperse cement effectively whereas allylether-maleic anhydride-based PCEs work better with silica fume. Apparently, PCEs with different molecular architectures are required to achieve optimum coverage of the different surfaces of cement and silica fume. Thus, a blend of methacrylate- and allylether-based PCEs used at approx. 0.5% by weight of cement is more effective than when they are utilized individually. To further enhance the performance of the formulation, sodium gluconate was introduced as a "supplemental" agent. The combination of PCE with gluconate allowed a reduction of approximately 50% in the dosage of PCE. The final blend contained 0.28% of allylether-based PCE and 0.10% of gluconate by weight of cement. A mechanistic study established that sodium gluconate adsorbs very strong on cement and to a less extent also on silica fume, whereas the allylether PCE almost exclusively adsorbs on the silica surface. Thus, the surface of cement is covered by gluconate molecules whereas the silica surface shows concomitant adsorption of both PCE and sodium gluconate molecules. The small gluconate molecules fill the space between the huge PCE molecules on the silica fume surface.

Cellulose ethers are polymers frequently introduced into mortar formulations in order to improve water retention capacity and workability of the freshly-mixed materials. Physico-chemical parameters of these admixtures (molecular weight, granulometry, substitution degrees, etc.) seem to have a strong influence on mortar water retention capacity. In this paper, the influence of cellulose ether particle size was studied. Two behaviors were highlighted regarding the particle size effect on mortar water retention. On the one hand, for cellulose ethers providing intermediate water retention, this parameter is fundamental: the thinner the particles, the better the water retention. The increase in water retention was explained by the rate of dissolution of every fraction which was faster for the thinnest particles. On the other hand, for admixtures providing strong water retention, the effect of this parameter was weaker or not relevant. Indeed, a cellulose ether concentration threshold was noticed, justifying this behavior.

Concretes with portland cement in the presence of fly ash or beneficiated fly ash (BFA) all at a slump of about 240 mm (9.4 in.) were made. Fly ash or BFA was used as mineral addition replacing 20% of portland cement in both plain and superplasticized concretes with or without shrinkage-reducing admixtures (SRA). The 28-day compressive strength of the superplasticized and plain concretes without mineral addition were higher than those of the corresponding concretes with fly ash and lower than that with BFA. Drying shrinkage of specimens exposed to a dry environment with relative humidity of 50% up to 4 months was measured. In the presence of fly ash the drying shrinkage decreased by about 15% with respect to the corresponding plain concretes without fly ash. In the presence of a superplasticizer and/or a SRA there was further reduction in dry shrinkage of fly ash mixtures. The drying shrinkage of concretes, where portland cement was replaced by BFA was lower than that of the corresponding concretes with fly ash. Even in the presence of superplasticizer and/or SRA a further reduction of drying shrinkage of BFA concretes was found. In fly ash or BFA concrete mixtures, and more significantly in the presence of superplasticizer and/or SRA, the cracking in restrained slabs was reduced in terms of both the number and the width of cracks.

Total Organic Carbon (TOC) measurement of cementitious pore solutions for quantification of (super)plasticizer adsorption was reviewed in this study with a system of two Polycarboxylate Ethers (PCE) and one Naphtalene Sulfonate polymer (BNS) in combination with 3 different cements. The influence of pore solution salt concentrations as well as different methods for pore solution extraction on the measured amount total organic carbon have been investigated. Adsorption measurements in paste, mortar and concrete systems are compared and conclusions are drawn by summarizing and interpreting the results obtained in the studies.